Engineering Solution-Processed Near Infrared Organic Photodetector
Neha Chauhan a b, Aiswarya Abhisek Mohapatra a, Suraj Yadav a, Arindam Ghosh b, Satish Patil a
a Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India
b Department of Physics, Indian Institute of Science, Bangalore, India
Proceedings of SUNRISE September Symposium 2021 ‘Powering Green Recovery’ (SUNRISEIII)
Online, Spain, 2021 September 20th - 22nd
Organizers: Hari Upadhyaya, Adrian Walters, James Durrant, Sara Walters and Georgia Bevan
Invited Speaker, Neha Chauhan, presentation 045
Publication date: 14th September 2021

Near infrared (NIR) organic photodetectors (OPDs) have huge potential in many disciplines from communication and astronomy to biomedical sciences owing to their large-scale solution processability, wearability, flexibility, tunability and cost-effectiveness. However, successful realization of OPDs still face major challenges such as less photon harvesting, poor photoresponse beyond NIR wavelengths due to relatively high bandgap and uncertainty in measuring accurate detectivity estimation using current protocols.

Significant progress has been made to extend the spectral range by synthesizing organic materials with low bandgap, different donor-acceptor dopant combinations, dopant dyes or incorporating additional absorber and a multiplication layer.1,2 However, these strategies compromise the achievable high EQE, low dark/noise current under bias and fast response time that are unfavourable for real-time photodetectors.

In light of challenges discussed above, this work focuses on tuning blend composition ratio in PM6:Y6 based bulk-heterojunction (BHJ) materials for building NIR sensitive fast organic photodiode. A photodiode vertical device architecture was fabricated where solution processing method was used to deposit the photoactive layer (PM6:Y6) sandwiched between ZnO (electron transport layer (ETL)) and MoO3 (hole transport layer (HTL), as shown in the schematic above. We could achieve a maximum photoresponsivity of 0.54 A/W at 830 nm for the optimized PM6:Y6 photodetectors, which is among the highest for binary blend BHJ organic photodetectors till date. Moreover, optimization process is still going on in our laboratory to further improve the NIR photoresponse by reducing the dark current and noise levels in the photodetector system and tune the spectral response beyond 1000 nm.



Z. Zhao, C. Xu, L. Niu, X. Zhang, and F. Zhang: Recent Progress on Broadband Organic Photodetectors and their Applications. Laser Photonics Rev. 14(11), 2000262 (2020).

Z. Wu, W. Yao, A. E. London, J. D. Azoulay, and T. N. Ng: Elucidating the Detectivity Limits in Shortwave Infrared Organic Photodiodes. Adv. Funct. Mater. 28(18), 1800391 (2018).

We acknowledge the financial support from IRPHA project of DST, the Government of India, and Raman Post-Doc Program, an initiative by the Institution of Eminence (IoE) by the Government of India at the Indian Institute of Science, Bangalore.

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